The present invention relates to a silicone composition which can be cured by both curing mechanisms of a moisture- or anaerobic-curing mechanism and a photocuring mechanism.
Silicone affords a soft cured material rich in elasticity and having high impact resistance, vibration resistance and thermal stress resistance, and thus it is a substance of high industrial utility value. However, the conventional one-pack type silicone requires a considerable time for complete curing because it undergoes a condensation reaction in the presence of moisture and cures. To avoid this inconvenience, a silicone which cures upon exposure to light has recently been developed. For example, a silanol terminated organopolysiloxane is treated with an aminoalkoxysilane to replace the end with amino group, and glycidyl (meth)acrylate is added thereto to render the siloxane photocurable (see JP55-112262A). However, since the glycidyl group and the amino group are less reactive with each other, it is necessary to conduct the reaction at a high temperature under heating for a long time or use a catalysts. As to the addition reaction of glycidyl (meth)acrylate, since the epoxy group and the acryl group are similar in reactivity to each other, the acryl group will undergo Michael addition reaction, resulting in photocurability being sometimes not imparted to the siloxane.
In JP61-t145227A, a silicone oil of amino chain and a vinyl group-containing isocyanate are reacted with each other, but the cured material obtained is very hard because of a side chain type and thus is unsuitable for potting or bonding although it is superior for coating or the like.
Further, in the reaction of a vinyl group-containing isocyanate with an amino group terminated silicone oil, if the amino group is a primary amino group, urea bond results, so that the proportion of hydrogen bond increases and the viscosity becomes very high, thus making it very difficult to handle the reaction product.
An anaerobic-curable silicone is also known. Generally, while in contact with air or oxygen, this silicone does not cure and is stable over a long period of time, but when air or oxygen is shut off, for example, between two adjacent faces, it polymerizes and cures, so is used for bonding, sealing or fixing metallic parts and the like.
Heretofore, as anaerobic-curable compositions of this sort, there have been known compositions each comprising a monomer consisting principally of an acrylic ester monomer and/or a methacrylic ester monomer and an organic peroxide as a polymerization initiator. In such uses as bonding, sealing and fixing, however, this kind of anaerobic-curable composition has a drawback such that when placed at a high temperature after anaerobic polymerization and curing, the bonding force of the cured materials is deteriorated rapidly.
In JP53-142493A, JP4-213363A and JP268315A there are proposed anaerobic-curable polyorganosiloxane compositions, but since the (meth)acryl group contained therein is a side chain type, the cured materials obtained from them are very hard and inferior in impact resistance, not being rich in rubbery elasticity.
It is the object of the present invention to overcome the above-mentioned drawbacks of the prior art and provide a silicone composition having high photocurability and moisture- or anaerobic-curability, easy to manufacture and easy to handle.